A susceptor having grooves

ABSTRACT

The invention relates to a susceptor for heating bodies by means of high frequency energy. The lower side of the susceptor comprises a profile which consists of longitudinal grooves present near the side surfaces. By means of said grooves on the lower side, a homogeneous temperature distribution is obtained on the upper side transversely over the susceptor.

United States Patent [19] van Dongen et a1.

[ Aug. 21, 1973 SUSCEPTOR HAVING GROOVES [75] inventors: Cornelius Johannes Adrianus van Dongen; Jacobus Michael Wilhelmus Hoisteede; Johannes Adrlanus Terburg, all of Nijmegen, Netherlands [73] Assignee: U. S. Philips Corporation, New

York, N.Y.

22 Filed: Feb. 16, 1972 21 App]. No.: 226,888

[30] Foreign Application Priority Data Mar. 6, 1971 Netherlands 7,103,019

[52] 11.8. CI. 2l9/l0.49, 118/49.5 [51] Int. Cl. H051) 5/04 [58] Field of Search 219/10.49, 10.41,

2l9/l 0.43, 10.61, 10.69, 10.79, 10.67; ll8/49.1, 49.5; 336/220; 13/1, 26

a ir

[56] References Cited UNITED STATES PATENTS 3,168,696 2/1965 Schoustedt 336/270 XR 3,524,776 8/1970 Hampikian et a1. l 18149.5 2,773,923 12/1956 Smith 2l9/l0.49 X 3,529,116 9 1970 Miyagi 2l9/l0.6l

Primary Examiner-J. ,V. Truhe Assistant Examiner-B. A. Reynolds Attorney-Frank R. Trifari [57] ABSTRACT The invention relates to a susceptor for heating bodies by means of high frequency energy.

The lower side of the susceptor comprises a profile which consists of longitudinal grooves present near the side surfaces. By means of said grooves on the lower side, a homogeneous temperature distribution is obtained on the upper,side transversely over the susceptor.

6 Claims, 4 Drawing Figures a x "IIIII'II; VIIIIIIIII D SUSCEPTOR HAVING GROOVES The invention relates to a method of treating a body, preferably a semiconductor body, which is present at a first surface of an elongate susceptor and which is heated by means of a high frequency energy source via the susceptor, said susceptor comprising a profile on a second surface opposite to the first surface.

The invention also relates to articles manufactured by means of the method, to a susceptor for use of the method, and to a device for carrying out the method. In known methods of the type mentioned in the preamble, the second surface of the susceptor comprises a profile having a substantially constant cross section viewed in the longitudinal direction of the susceptor, while in the centre of the said surfaces the susceptor is thinner than at the side surfaces.

It has been found that a homogeneous temperature distribution transverse to the longitudinal direction over the first surface of the susceptor cannot always be obtained by means of such profiled susceptors and that the said temperature distribution is often less satisfactory than that of a non-profiled susceptor.

It is one of the objects of the invention to avoid the said drawback at least for the greater part. The invention is based on the recognition of the fact that a more homogeneous temperature distribution can be obtained with a quite different profile.

According to the invention, the method mentioned in the preamble is characterized in that asusceptor is used the profile of which consists of grooves which extend tion transverse to the longitudinal direction over the 7 first surface of the susceptor. A susceptor is preferably used, the profile of which consists of one groove along each of the side surfaces.

In the method according to the invention, inwhich material of the bodies is removed, for example, with a gas etching treatment, or is deposited on them, for example, in the case of epitaxy from the gaseous phase, the advantages of the new profile become apparent. The speed of such reactions is often strongly temperature-dependent and so is the incorporation of doping materials which are present in the gaseous phase and influence the electric resistance of the deposited material. It has now been found that in the case of epitaxy from the gaseous phase and with simultaneous incorporation of doping materials the electric resistance of the material deposited on the bodies varies much less con-. siderably in the transverse direction of the susceptor in the cases in which susceptors according to the invention are used than when susceptors are used having a known or no profile. Such a method is preferably carried out in a device which comprises at least one susceptor according to the invention.

The invention also relates to a semiconductor device which is manufactured from a semiconductor body treated while using the last-mentioned method. Such semiconductor devices which otherwise are manufactured in any conventional manner, have readily reproducible properties and are obtained in comparatively large yields.

In order that the invention may be readily carried into effect, one embodiment thereof will now be described in greater detail, by way of example, with reference to the accompanying drawing, in which FIG. 1 shows temperature distributions corresponding to places on susceptors which are shown in FIG. 2 to 4 FIG. 2 is a cross-sectional view of an unprofiled susceptor transverse to the longitudinal direction FIG. 3 and 4 are cross-sectional views transverse to the longitudinal direction of susceptors according to the invention.

The temperatures shown in FIG. 1 are the temperatures which have been measured on semiconductor bodies 1 on the first surface 2, 3 or 4 of the susceptors 5, 6 or 7 in the places denoted by the crosses (see FIG. 2, 3 and 4).

The susceptors are 400 mm long, 116 mm wide and 13 mm thick. The susceptors are of graphite. The susceptor shown in FIG. 3 comprises, at 7 mm from the side surfaces 9, grooves 8 which are 4 mm deep and 6 mm wide. The susceptor 7 shown in FIG. 4 has, at 7 mm from the side surfaces 10, grooves 11 which are 5 mm deep and 6 mm wide. As compared with the unprofiled susceptor 5 shown in FIG. 2, the temperature distribution, over a 92 mm wide region, has decreased from 27-30+ C to approximately 16 C in the case of the-profiled susceptor 6 shown in FIG. 3 and to 14 C in the case of the susceptor shown in FIG. 4, and the distribution of the susceptor shown in FIG. 2, over a range of 78 mm wide, from 20 C to approximately 9 C in the susceptor shown in FIG. 3 and approximately 5 C in the susceptor shown in FIG. 4.

It has moreover been found that, in. the case of epitaxy on a semiconductor body of silicon which is heated on a susceptor according to the invention, the spreading in the resistance of a dopeddepositedsilicon layer decreases by a factor 5 in certain cases.

The above-mentioned dimensions are given only by way of example. The grooves may be wider, for example. The optimum dimensions of the grooves are also influenced by the wayof cooling the device in which the susceptors are used and by the major dimensions of the susceptor.

We claim:

l. A susceptor for uniformly heating in a high frequency field a substance in contact therewith compris- 1 ing a body having two opposed major surfaces, one major surface having two opposed edges and two grooves, each groove being substantially coextensive with and respectively spaced adjacent to said opposed edges, whereby when said body isin a high frequency field, said grooves effectively increase the heat generated by said field in said. body in the region of said grooves resulting in a more substantially homogeneous heat distribution at the other major surface and in substance in contact therewith.

2. A susceptor as set forth in claim 1 wherein said opposed major surfaces are flat parallel planes.

3. A susceptor as set forth in'claim l wherein said body is rectangularly shaped and said grooves are parallel with said opposed edges and respectively spaced from said edges by a distance less than the distance between said opposed'major surfaces.

4. A susceptor as set forth in claim 3 wherein said grooves are rectangularly shaped with a width less than the distance between said opposed major surfaces and a depth less than half the distance between said opposed major surfaces.

5. A susceptor as set forth in claim I wherein said body is composed of graphite.

6. A susceptor as set forth in claim 1 adapted to be placed in contact with a semiconductive body for homogeneous heating of said semiconductive body.

i i I t t 

1. A susceptor for uniformly heating in a high frequency field a substance in contact therewith comprising a body having two opposed major surfaces, one major surface having two opposed edges and two grooves, each groove being substantially coextensive with and respectively spaced adjacent to said opposed edges, whereby when said body is in a high frequency field, said grooves effectively increase the heat generated by said field in said body in the region of said grooves resulting in a more substantially homogeneous heat distribution at the other major surface and in a substance in contact therewith.
 2. A susceptor as set forth in claim 1 wherein said opposed major surfaces are flat parallel planes.
 3. A susceptor as set forth in claim 1 wherein said body is rectangularly shaped and said grooves are parallel with said opposed edges and respectively spaced from said edges by a distance less than the distance between said opposed major surfaces.
 4. A susceptor as set forth in claim 3 wherein said grooves are rectangularly shaped with a width less than the distance between said opposed major surfaces and a depth less than half the distance between said opposed major surfaces.
 5. A susceptor as set forth in claim 1 wherein said body is composed of graphite.
 6. A susceptor as set forth in claim 1 adapted to be placed in cOntact with a semiconductive body for homogeneous heating of said semiconductive body. 